In the first two decades of the 2000s Frisco, Texas, was swallowed up by the Dallas-Fort Worth metroplex, becoming both a corporate center — think Dallas Cowboys — and a bedroom community for commuters heading to one city or the other. From a population of 33,000 in 2000, according to U.S. Census figures, Frisco swelled to 210,000 residents in 2023 and still is growing. 

All of these developments could be a threat to the local lakes that provide water for more than 5 million people. Frisco is doing its part to avoid having the detritus of urban development ruin the area’s growth experience. The city’s stormwater department is doing such a good job, in fact, that it took home top honors from the 2022 Water Environment Federation’s Stormwater and Green Infrastructure awards program.

The gold medal awards annually cite municipal separate stormwater systems that are especially well-managed and innovative. Frisco was declared the overall winner in Phase II (larger) cities, which included places like St. Louis and Richmond, Virginia.

The honors to the city came on Perry Harts’ watch. Harts has been Frisco’s stormwater manager for a dozen years, so he has been there for much of the community’s mushrooming growth. Frisco was, in fact, deemed for several years to be the nation’s fastest growing city, that distinction coming as late as 2017.

Needless to say, all the growth and expansion poses a huge pollution risk to streams leaving Frisco. “Construction is an enormous factor for us. That has been the biggest specific challenge,” Harts says.

About 1,400 building permits are active in the city at any given time and hundreds of civil engineering projects are undertaken annually. “These pose enormous risk for our streams,” Harts says. “We spend most of our time ensuring controls are in place and contractors are in compliance.”

The department conducts two kinds of inspections — the first of actual infrastructure construction areas and other work sites to inspect runoff mitigation efforts, the second of paperwork to see if contractors are in regulatory compliance.

“Just making sure contractors are familiar with the regulations, that’s the hard part,” says Christopher Collis, the department’s inspections supervisor.

Innovative thinking

The waters the department is trying to protect are both visible and out of sight. Some 140 miles of rippling streams ramble through the community’s boundaries. Beneath the surface of the city, water is channeled through 889 miles of stormwater pipe. Harts notes that “any manmade infrastructure requires a lot of attention. In comparison, natural streams have been running along for thousands of years and require very minimal work.” Still, both situations need managing and Frisco’s stormwater department is on top of it. 

As for the innovation piece of the environmental awards, it’s easily explained: Harts and his crew like to try new things. From fallen trees to beaver dams, the department often responds in novel ways.

Example: A tall hardwood tree on the edge of a stream was uprooted and fell into the creek bed. “The tree was upstream of a sewer line that crosses the creek,” Harts explains. “Our concern was that it could float downstream and break the sewer line. We at first figured we would chop up the tree and remove it, but upon looking at it, we decided to use it.”

Specifically, the fallen tree was repositioned and anchored in place. Subsequent rainstorms deposited silt in and around the tree’s trunk and branches and began to rebuild the embankment in an eroded area. “We took a problem and turned it into a solution. That was a team idea.”

Something similar was done using discarded Christmas trees. In an area of a stream where banks were badly eroded, the trees were anchored several feet apart and perpendicular to the stream. As water rose and fell after passing storms, silted material piled up against the evergreens. Plants of one kind or another then took root to further retard erosion.

The city has long required “water resource zones” adjacent to the parking areas of new developments. These areas filter pollutants from stormwater as it travels through the vegetation and into the soil. Unfortunately, most developers used exotic plants in the zones, which are not as sustainable as native prairie grasses and plants. When the city built a parking lot in 2015, the stormwater division created a different kind of absorption area as a demonstration project. The purpose was to show the advantages of using native plants and native soil in the zones.

The plot quickly became a self-sustaining natural area with deeply rooted plains, grasses and flowers. More importantly, infiltration tests showed the natural areas were amazingly more receptive to rainwater, quickly absorbing it and thereby reducing runoff. The comparison was stark: Engineered soils with sand content infiltrate at a rate of 3 1/2 inches an hour, whereas the natural areas suck down water at the rate of 51 feet an hour!

Another example of innovative thinking occurred when a stream was repeatedly blocked by beavers. The department responded by cutting a passage through the beaver dam with a mini-excavator and placing a length of flex culvert material in the trough. The ends stuck out several feet past the dam with cages protecting them against being plugged either by energetic animals or floating debris.

“We called it our beaver-deceiver,” Harts says. The beavers returned and built their dam atop the culvert, but the water kept flowing beneath it through the pipe. Brandon Smith, stormwater supervisor, says the solution was a decisive one. “The beavers gave up trying to block the stream, so we took out the pipe. It wasn’t needed anymore.”

Perhaps the department’s single most innovative achievement is what Harts calls “one of the neatest projects. Our trash rack.” It was conceived and built because the city’s environmental permit requires collection of “floatables” — both constructed and natural floating debris. When the collector was needed, rather than spend a hundred thousand dollars on a commercial concrete structure, the division team built one.

The structure was crudely sketched out by a crew member and fabricated in the shop. The tubular iron structure consists of two hinged open-faced gates that meet in the middle, with heavy-gauge plastic trash bags affixed to the downstream side of them. As the water trickles through them, floating debris is culled and deposited in the bags, which are periodically replaced.

During periods of normal stream levels, concrete parking abutments placed on either end of the gates funnel the shallow stream of water to where the bags can catch the floatables. In heavy rain events, the gates swing open rather than block the flow and are reset afterwards. In 2022, the device captured about a ton of floating debris.

“It is effective and efficient,” says Harts, who is a professional engineer. He’s not alone in his estimation. The North Texas Council of Governments sent their engineers to study the structure and replicated its design in fine-drawn detail. The debris-catcher solution then was offered to municipalities in the council. While it isn’t patented, Harts says Frisco worked with a patent attorney to ensure that the design would remain in the public domain.

Deeper layers

The entire stormwater department in Frisco numbers 16 people. Six of them are dedicated to maintaining the system, whether underground or in plain sight.

The department equipment yard contains a couple of backhoes and mini-excavators, a crane truck, a grapple truck and, probably the most interesting piece of heavy equipment, a HARD-LINE LP401 remotely controlled low-profile skid-steer loader. Among other tasks, the tracked LP401 is called upon to muck out silted stream beds near bridges.

The department has a CGI drone with which it monitors streams. It also has stream assessment gauges fixed in place at three places around town. The devices give real-time readings on data such as oxygen content, salinity and the pH level in the water. It’s all good reading for department hydrologist Sean Aucoin.

“By looking at deeper layers of issues at a location (including the history of adjoining properties), we are able to monitor the stream more efficiently,” says Aucoin. “Having the monitors in place prevents us from needing to go out there in person on a regular basis with the hand monitors.” In the next year, three more of the fixed assessment monitors will be placed in streams on the eastern side of Frisco.

Surveying streams from the air with drones and monitoring moving water with the in-place gauges lets the department keep close watch on streamwater and erosion along banks. Underground flows are inspected using cameras. When clogging conditions are seen there, an appropriate pipe cleaning response is initiated. “Most of our problems are identified through inspections,” says Harts, meaning they are attentively ferreted out before they become big problems.

The expansion of the stream assessment gauge system suggests Frisco’s stormwater crew will not rest on its gold award laurels. Harts says the stormwater team has talked about the need to keep pushing, to keep managing in innovative ways.

One planned response is to increase the use of unmanned aerial vehicles. “In the future, we want to do a lot more with drones. It’s cheaper than putting an engineer in the creek and we get more accurate data. We can fly each creek a couple of times a year and find places that need attention.”

The little unmanned aerial vehicles also are going underground. “The drone world really has changed in the last few years. We are looking at ways to use drones inside stormwater pipes, which is a real game-changer.” Harts says not only does a drone not have to drag a cable into a pipe, the inspection cost less. Typical camera inspections cost about $10 a foot, according to the stormwater manager.

The department also has begun to emphasize maintenance of separators on commercial properties. The devices are supposed to treat and control stormwater runoff after builders have moved on to other jobs and a property owner has assumed responsibility for runoff.

“An example is a strip mall that has a mechanical separator,” says Harts. “If those devices aren’t maintained, they are worthless. If you own a strip mall, you have lots of things on your mind, such as tenants and profits, and the mechanical separator is the last thing you think about. We have one stormwater inspector who is dedicated to looking at the separators post-construction.”

If a separator is found to be non-functioning, the department has legal recourse. A department engineer approves a separation system during construction and, once approved, the developer is required to keep it working. If they don’t, says Harts, “we can enforce it by ordinance.”